package me.zk.practice1;

import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @Author: zhang kai
 * @Date: 2022/10/31
 * @Description:
 */
public class Solution4 {

    static Object a;
    public static void main(String[] args) {
        Collections.synchronizedMap(new HashMap<>());
        new ConcurrentHashMap();
        Map map = new Hashtable<>();
        map.put(a, new Sub());
        new LinkedHashMap<>();
        new TreeMap<>();
        new HashSet<>();
        "".hashCode();

    }

}

interface a{}
interface b{}
interface c extends a,b{

}
